The present invention relates to a new and improved construction of a cant segment-radial bearing--also referred to as a tiltable segment-radial bearing--for heavily loaded high-speed shafts, especially the shafts of turbo sets and drives, typically turbo-generator units, athough other fields of application are obviously contemplated.
Generally speaking, the cant segment-radial bearing is of the type comprising at least one support segment arranged to be cantible or tiltable in the load direction of a bearing housing and at least two guide segments arranged in the counterload direction of the bearing housing. Intermediate spaces are provided between the individual segments and a lubrication circulation system is provided which contains an infeed line, opening into the bearing housing, for a cooled lubricant which is under pressure.
Cant segment-radial bearings of the type here of interest are particularly used in conjunction with shafts having a circumferential speed of 70 m/sec and more at the outermost bearing journal diameter.
Such bearings have been disclosed, for instance, in German Pat. Publication No. 2,154,217 and the publication entitled "Brown Boveri-Mitteilungen", Nr. 6-77, pages 309 to 320. They have been developed in an attempt to provide a bearing which is capable or withstanding high specific loads and having as small as possible energy losses. It is known that the bearing losses at large turbo sets usually are in the order of magnitude of 0.5% of the machine output and, even in there is provided particularly advantageous bearing constructions, hardly can be reduced below 0.3%. Therefore, it will be readily perceivable that with a machine having a 1300 megawatt output there still exist power losses in the order of magnitude of 4,000 to 6500 kilowatts. Notwithstanding cooling of the lubricant within a cooling unit arranged externally of the bearing the bearing losses lead to pronounced heating of the segments, and thus, the specific loadability must be held within very narrow limits. In the case of highly loaded shafts, for instance shafts of turbine rotors having a mass of 100 tons and more, it is therefore necessary to have bearing journal diameters up to 900 milimeters. However, the larger the bearing journal diameter that much greater is the circumferential speed for a given rotational speed, and this in turn again is decisively responsible for heating of the lubricant in the bearing gaps.